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Why Storm-Based Warnings?

Example of county based warningsExample of storm based warnings
NOTE: A higher resolution version of these graphics is available for download (2.62 MB TIF file).

The National Weather Service (NWS) mission is defined as the provision of weather forecasts and warnings for the protection of life and property and the provision of weather information for the Nation’s economic well-being. The NWS previously issued and disseminated warnings for tornado, severe thunderstorm, flood and marine hazards using geopolitical boundaries. Realizing the continuing need to improve the specificity and accuracy of warnings for tornadoes, severe thunderstorms, floods and marine hazards, the NWS currently implements Storm-Based Warnings (as of October 1, 2007).

Storm-Based Warnings (threat-based polygon warnings), are essential to effectively warn for severe weather. Storm-Based Warnings show the specific meteorological or hydrological threat area and are not restricted to geopolitical boundaries. By focusing on the true threat area, warning polygons will improve NWS warning accuracy and quality. Storm-Based Warnings will promote improved graphical warning displays, and in partnership with the private sector, support a wider warning distribution through cell phone alerts, pagers, web-enabled Personal Data Assistants (PDA), etc. NOAA Weather Radios will work as before and continue to alert entire counties.

Department of Commerce
National Oceanic & Atmospheric Administration
National Weather Service
Office of Climate, Water, and Weather Services
Warning Decision Training Branch
120 David L. Boren Blvd.
Norman, OK 73072
Page Author: WDTB Webmaster
Page last modified: February 26, 2008 13:50

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